1. Field of the Invention
The present invention relates to: a material for forming an adhesion reinforcing layer which can reinforce the adhesion between a low dielectric constant film and other members, in particular between a low dielectric constant film containing an inorganic material and other members; an adhesion reinforcing layer which is formed by the material for forming an adhesion reinforcing layer and exhibits superior adhesion; a semiconductor device having the adhesion reinforcing layer, which is fast and highly reliable; and a manufacturing method thereof.
2. Description of the Related Art
The acting speed of a semiconductor device has long been increased according to the scaling law by miniaturizing the semiconductor device. The recent high-density semiconductor integrated circuit device has a multi-layer wiring structure in wiring between individual semiconductor devices. In the multi-layer wiring structure, however, adjacent wiring patterns in the multi-layer wiring structure are in contiguity with each other, and a problem of wiring delay occurs due to a parasitic capacitance between the wiring patterns since the semiconductor devices are extremely miniaturized. The parasitic capacitance is inversely proportional to the distance between the wiring patterns and directly proportional to the dielectric constant of an insulator located between the wiring patterns.
Given this factor, the use of a material with low dielectric constant for the inter-layer dielectric constant film (the insulating film) in the multi-layer wiring structure for the reduction of the parasitic capacitance has been examined in order to improve the issue of the wiring delay.
Regarding the dielectric constant of the inter-layer insulating film, the dielectric constant of a conventionally-used CVD-SiO2 film is about four, and the dielectric constant of an SiOF film, which is formed by the addition of fluorine to the CVD-SiO2 film for further reduction of the dielectric constant, is about 3.3 to 3.5 at best. In addition to these, a polyallylether material has been considered as an organic insulating material, but the dielectric constant is about 2.6 to 2.9 at best. Therefore, none of the above-mentioned materials provides sufficient effect of reducing the parasitic capacitance in the recent high-density semiconductor integrated circuit, and there has been a problem that a required acting speed cannot be met.
In this regard, the use of a porous insulating film as a so-called low dielectric constant inter-layer insulating film with a lower dielectric constant has been focused. The porous insulating film is formed by: adding an organic resin which evaporates or decomposes upon heating to a coating material; then, applying the coating material by spin coating method; and finally heating to evaporate or decompose the organic resin so that the porosity is provided to the insulating film. In this case, the dielectric constant is reduced to 2.5 or below; therefore, the possibility of applying the porous insulating film to a semiconductor device as a low dielectric constant inter-layer insulating film has been examined.
Incidentally, since the wiring delay is proportional to the product of the parasitic capacitance between wiring and the wiring resistance, the reduction of resistance in the wiring itself by employing Cu with low resistance in place of conventionally-used Al as a wiring material. In this case, it is necessary to prevent the dispersion of the cupper atoms within the wiring into the inter-layer insulating film, and the arrangement of a copper barrier film containing mainly silicon carbide (SiC) and silicon oxycarbide (SiOC) has been attempted.
However, the formation of the porous insulating film on the copper barrier film reduces the contact area with the copper barrier film compared to the conventional insulating layer since the porous insulating film consists of many pores; therefore, there is an issue of decrease in adhesion. The decrease in adhesion causes an interfacial debonding between the low dielectric constant insulating film and the copper barrier film when a multi-layer wiring is formed, and the problem of the interfacial debonding becomes prominent as the number of the wiring layer increases. In addition, the problem of interfacial debonding occurs due to the reduction in adhesion in laminating not only the copper barrier film but also other films.
As a method for improving the adhesion between the insulating film and the copper barrier film, for example, a surface treatment of the copper barrier film with a silane coupling agent is known (Japanese Patent Application Laid-Open (JP-A) Nos. 2001-345317, 2002-40673, 2002-38081 and 2004-532514). Although they are quite effective in improving the adhesion between an inorganic material and an organic material such as combination of the copper barrier film and an organic insulating film, they are almost ineffective in improving the adhesion between inorganic materials such as combination of the copper barrier film and the porous insulating film. In addition, alkoxysilane contained in the silane coupling agent is highly reactive with water, causing a hydrolysis reaction. Therefore, the solution has extremely low preservation stability, and the application to manufacturing semiconductor devices has been difficult.
Hence, the material for forming an adhesion reinforcing film which can provide superior adhesion between films made of inorganic materials as well as reinforce the adhesion between the low dielectric constant film and other members, and related technologies employing thereof has not currently been produced yet.
The present invention is aimed at resolving the above issue and achieving the following object. That is, the object of the present invention is to provide: a material for forming an adhesion reinforcing layer which can reinforce the adhesion between a low dielectric constant film and other members, in particular between a low dielectric constant film containing an inorganic material and other members; an adhesion reinforcing layer which is formed by the material for forming an adhesion reinforcing layer and exhibits superior adhesion; a semiconductor device having the adhesion reinforcing layer, which is fast and highly reliable; and a manufacturing method thereof.
Regarding the above-mentioned issues, keen examinations by the inventors resulted in the following insights. That is, it was observed that the use of a material for forming an adhesion reinforcing layer including at least any one of organoalkoxysilane having a basic functional group, a basic additive and organoalkoxysilane produces superior adhesion between inorganic materials and that an adhesion reinforcing layer which can reinforce the adhesion between the low dielectric constant film containing an inorganic material and other members may be achieved. Also, the inventors discovered that the material for forming an adhesion reinforcing layer had favorable preservation stability for its basicity. These insights lead to achieving the present invention.